Write stream files with a selection of the reflections from another stream file about sfx_utils HOT 1 CLOSED

Thanks for creating an issue for this, Fred! Much easier to keep track of to-do's this way.

Note to self on this topic: it may be useful to additionally keep track of the chunk number in the stream_data self variable to simplify generating a new stream file with select reflections. This way, if a chunk doesn't have legitimate reflections, it can be skipped altogether.

Second note to self on this topic: the stream_data variable is a bit unwieldy, so it may be worth adding one-line functions to the StreamInterface class that returns the correct column of stream_data when called.

from sfx_utils.